The present invention generally relates to fuel-fired heating appliances and. In a preferred embodiment thereof, more particularly relates to a fuel-fired water heater provided with a normally closed air inlet damper structure which, during non-firing periods of the water heater, functions to prevent entry of extraneous flammable vapors into the water heater combustion chamber through perforations in a flame arrestor wall portion thereof.
In a conventional fuel-fired, power vented water heater an intermittent pilot ignition structure within the water heater's combustion chamber is utilized to ignite the main burner therein when an associated thermostat calls for heat to be delivered to the water stored in the tank portion of the water heater. During idle, non-firing periods of the water heater (when both the main burner and the associated pilot ignition structure are not operating) ambient air near the combustion air inlet portion of the water heater may be drawn into the combustion chamber by, for example, a natural draft effect within the flue portion of the water heater.
This incoming combustion air may carry with it extraneous flammable vapors if they are present adjacent the water heater. When the next demand for heat occurs, and the pilot structure is ignited to start the main burner, an undesirably hard ignition may occur in the combustion chamber when a buildup of such flammable vapors occurs therein. It would thus be desirable to provide this type of fuel-fired water heater with apparatus for preventing a combustion chamber inflow of combustion air and extraneous flammable vapors during non-firing periods of the water heater. It is to this goal that the present invention is directed.